
Instead of a passenger seat you'll notice there's an unusual cylindrical canister - that's the flywheel accumulator. Each of the 918's front wheels has an electric motor/generator, which can both drive the wheels for extra oomph or generate electricity during braking.
The energy they generate is captured and stored in the accumulator, which can spin to a dizzying 36,000rpm. The driver can press a button at any point and unleash this energy back to the motors for an instant hit of power - a kind of futuristic rocket boost, if you will.